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Shielding a Linear Heathkit Power Supply

Discussion in 'Power Electronics' started by Supercap2F, Jun 22, 2015.

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  1. Supercap2F


    Mar 22, 2014
    Hey Guys! :)

    Okay, so I've had a Heathkit IP-2715 power supply sitting in the garage for a while and recently I decided to build up a shelf for it and my O-Scope (and maybe some more test gear soon) in my lab. So after finishing the wood shelf, I decided to try out the setup to see if everything worked nicely in it's location. After turning on my O-Scope, I switched on the power supply and everything on the scopes CRT shifted downwards.

    I assume that this was because of the huge linear transformer in the power supply (it weighs a ton!). So I moved the power supply away from the scope and everything went back to normal.

    Now my question is, is there any good way to shield the O-Scope form the power supply? Like maybe a sheet of some sort of metal between the shelfs? And even if I do shield it, could the smaller amount of stuff that gets through (since no shield is perfect) potentially damage/throw out the calibration on my O-Scope over time?

    Thanks for your time guys!! :)

    P.S. the schematic for the power supply can be found here.
  2. ramussons


    Jun 10, 2014
    In all probablity, it's the Magnetic Field from the Transformer causing the Beam Deflection. A soft iron shield should give good protection if it is thick enough.

    If the magnetic radiation is power based at 50 or 60 Hz, there is not likely to be any permanent damage in the long run. But if the magnetic field is unidirectional, it can lead to side effects over time.

    CRT picture tubes had a de-magnetising coil to offset the effect of permanent mag fields, not too sure if all oscilloscopes have something similar.
    Supercap2F likes this.
  3. Supercap2F


    Mar 22, 2014
    Okay, yeah I thought it might be something to do with the magnetic field from the transformer. Do you know of any good places to get soft iron sheets? I had a look at some of my local hardware stores websites, and it didn't look like they had any...

    The power supply is hooked up to the mains, so it's running at 120V 60Hz... I guess that means it would be safe to have to scope close?

    Thanks a Ton for the advice ramussons!! :)
  4. Minder


    Apr 24, 2015
    CRT's typically had Mu-metal sleeve over the tube for shielding.
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